The present invention relates to a novel organosilicon compound and a room temperature curable organopolysiloxane composition with improved curability containing the novel organosilicon compound as an essential component.
There are known several types of room temperature curable organopolysiloxane compositions or so-called RTV silicone rubbers, i.e. room temperature vulcanizable silicone rubber compositions, curable at room temperature into a rubbery elastomer. These RTV silicone rubber compositions are classified from the standpoint of practical use into two classes of the so-called two-package type and one-package type ones. The compositions of the former type are supplied in two packages containing different components or premixes of components to be blended directly before use in order to avoid premature curing while the compositions of the latter type are supplied as a read-mixed blend of all of the components by virtue of the storage stability thereof and usable without blending of the components before use.
In connection with the mechanisms involved in the crosslinking reaction, RTV silicone rubber compositions are further classified into several classes. For exammple, many of the RTV silicone rubber compositions are cured by the mechanism of a condensation reaction producing different condensation products such as carboxylic acids, e.g. acetic acid, alcohol compounds, aminoxy compounds, amine compounds, oxime compounds and the like according to the types of the functional groups pertaining to the condensation reaction. The carboxylic acid, aminoxy, amine and oxime compounds are, however, toxic or corrosive so that the RTV silicone rubber compositions emitting these noxious gases by curing cannot be used in contact with metals and must be used under good ventilation. The RTV silicone rubber compositions of the dealcoholation type are of course free from the problem of the emission of noxious gases but, on the other hand, disadvantageous due to the insufficient storage stability and the relatively low curing velocity as well as poor mechanical properties of the cured rubber with fragility.
Further, it is a usual practice that some of the RTV silicone rubber compositions are admixed with certain curing accelerators or curing cocatalysts such as titanium alkoxide compounds, metal salts of organic acids and the like. The addition of such an auxiliary ingredient, however, involves serious disadvantages caused by the adverse effects of the ingredient remaining in the cured rubber on the coloration and physical and chemical properties of the rubber even by setting aside the toxicity of some of the metallic components. In this regard, RTV silicone rubber compositions curable by the mechanism of deketonation condensation have been developed (see, for example, Japanese Patent Publications Nos. 51-39274, 51-39673 and 54-44669 ). Although these compositions are satisfactory in respects of the adhesiveness to the substrate surface and corrosiveness, they are not suitable for use where a large ultimate elongation of the cured rubber is desired.